Method and apparatus for notifying parameter changes of access control mechanism

ABSTRACT

According to one exemplary embodiment, the method includes configuring, in a system information block, a parameter of the access control mechanism which indicates a first access class of the multiple access classes is barred; transmitting a first paging message which includes an indicator indicating the parameter of the access control mechanism has been modified; not allowing any random access associated with the first access class in response to the first access class being barred; configuring, in the system information block, the parameter of the access control mechanism, wherein the parameter of the access control mechanism indicates the first access class of the multiple access classes is no longer barred; transmitting a second paging message which comprises the indicator indicating that the parameter of the access control mechanism is modified; and allowing a random access associated with the first access class after the first access class no longer being barred.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of and claims thepriority benefit of a prior continuation application Ser. No.15/679,169, filed on Aug. 17, 2017, now pending. The above describedcontinuation application claims the priority benefit of a priordivisional application Ser. No. 14/562,760, filed on Dec. 7, 2014, nowabandoned. The prior divisional application is a divisional applicationof and claims the priority benefit of parent application Ser. No.13/658,801, filed on Oct. 23, 2012, now patented as U.S. Pat. No.8,942,091, issued on Jan. 27, 2015. The prior application Ser. No.13/658,801 claims the priority benefit U.S. provisional application Ser.No. 61/557,424, filed on Nov. 9, 2011. The entirety of each of theabove-mentioned patent applications is hereby incorporated by referenceherein and made a part of specification.

BACKGROUND Technical Field

The present disclosure relates to a method used by a base station fornotifying a specific access class of multiple access classes ofparameter changes of an access control mechanism and a base stationusing the same.

Related Art

Machine Type Communication (MTC) is a novel communication techniqueamong machines and often involves communications either with verylimited human interventions or completely without. Implementations ofMTCs may be evident in the practical applications such as metering,transportation, health care system, remote maintenance, and etc.

The MTC has several characteristics: First of all, the populationdensity of MTC devices is generally much higher than human to human(H2H) communication devices. Second of all, MTC devices are usuallyconsidered to have lower communication priority than H2H devices. Thirdof all, the MTC devices can be behaviorally unpredictable as they maynot exhibit a regular pattern as to when they may require networkresources. Based on these three characteristics, if an enormous quantityof MTC devices attempt to attach to a network, the MTC devices wouldeasily consume all the network resources and cause overloading to thenetwork. In order to prevent network congestions or overloading, ameasure to curtail this type of problem is required.

For the 3^(rd) Generation Partnership Project (3GPP) Long Term Evolution(LTE) communication system, the Extended Access Barring (EAB) scheme hasbeen introduced to prevent congestion or overload in the Radio accessnetwork (RAN) or in the Core Network (CN). EAB is a mechanism for whichrandom access (RA) attempts from MTC devices can be controlled. In LTE,each user equipment (UE) may be classified into one of the AccessClasses (AC) between 0 to 9. When a LTE resource channel, the PhysicalRandom Access Channel (PRACH), is too congested, the EAB scheme couldmitigate PRACH congestion by barring some ACs of MTC devices fromaccessing the network. EAB parameters are located in the SystemInformation Blocks (SIBs) of the System Information (SI) which isbroadcasted periodically by the LTE Network through the BroadcastControl Channel (BCCH). Since the EAB parameters are treated as a kindof System Information (SI) in LTE, it would need to be updated withinthe SI according to a prescribed updating mechanism. However, theprescribed SI updating mechanism possesses shortcomings in which theupdating mechanism is rendered ineffective in coping with the networkoverload problem.

Specifically, the SI in LTE cannot be modified at any time. Only at eachModification Period Boundary (MPB) would the SI be allowed to bemodified. Supposedly if the MPB is set to be 640 milliseconds (ms), theSI would then only be allowed itself to be modified once every 640 ms.Based on the MTC characteristics as previously mentioned, if an enormousquantity of MTC devices were to perform RA attempts, the EAB schemecannot be enacted soon enough to curtail PRACH overloads since the EABparameters cannot be immediately updated according to the currentlyprescribed updating mechanism.

To order to circumvent the restriction caused by the MPB, two mainschools of thoughts have been proposed for LTE. The first proposedmethod is mandate reading of the EAB information for each MTC before anaccess. The second proposed method is notification of EAB informationupdate through paging.

For the first proposed method, the network would not be restricted bythe MPB as the network could update the EAB parameters any time at anyEAB-SIB, the specific system information block of the SIBs whichcontains the EAB System Information. The network could update the EABparameters without any notifications to the MTC devices. However, theMTC devices would be required to obtain the EAB-SIB before any attemptsto access the network.

For the second proposed method, the network also would not be restrictedby the MPB as the EAB information could be updated any time at anyEAB-SIB. The difference from the first proposed method is that thenetwork is required to notify the change of EAB parameters throughpaging, which means that the MTC would be paged by the network pagingchannel. For the second proposed method, any EAB status change wouldtrigger the network to send a paging message containing an EAB changenotification. The EAB status change may include the EAB enable, any EABparameters change, or the EAB disable. When the EAB status change isdetected from a paging message, the MTC would only know that the EABstatus has been changed through being able to distinguish what kind ofchange has been implemented. Therefore, in order to acquire the latestEAB status, any MTC device which receives the page containing the EABchange notification would be requested to acquire the EAB-SIBimmediately.

For example, if the EAB is enabled by a base station (BS) or eNodeB(eNB), a paging message containing EAB change indicator which equalstrue would be transmitted to any MTC device within a receiving range.When the paging message is received by a MTC device, the EAB-SIB wouldimmediately be acquired. If the EAB parameter is changed by an eNB, apaging message containing EAB change indicator which equals true wouldalso be transmitted to any MTC device within a receiving range andcaused the MTC devices to acquire the EAB-SIB. Similarly, if the EAB isdisabled by an eNB, a paging message containing EAB change indicatorwhich equals true would also be transmitted to any MTC device within areceiving range and caused the MTC devices to acquire the EAB-SIB. Butif a normal paging, meaning paging not involving EAB, is made, the EABchange indicator would equal false, since the EAB change indicator wouldonly indicate a EAB status change.

Comparing both proposed update mechanisms, the first proposed method hasan advantage of being able to modify the EAB information without havingto first notify MTC devices. The other advantage is that there would beno impact on H2H UEs and on MTC devices which do not attempt to accessthe network. However, the disadvantage is that the MTC devices wouldhave to acquire EAB-SIB whenever they perform a RA to the network. SinceEAB might be a relatively rare event, the MTC devices would consumepower needlessly only to find out that the EAB has not been enacted.Also acquiring the EAB information before RA attempt would cause somedegrees of synchronous access problem which will happen after MTCdevices acquire EAB-SIB and discover that the EAB is still disabled ordiscover that they are not actually barred by the EAB.

On the other hand, for the second proposed method, has an advantage ofnot causing synchronous access problems and unnecessary SIB acquisitionswhen EAB is disabled. However, a disadvantage is that there would be ahigh paging overhead since the network would use paging messages tonotify each EAB update to MTC devices, and also the network might changeEAB parameters frequently such as to rotate barred access classes or toremove the baring in gradual steps. Also it would not be necessary torequire all MTC devices to immediate obtain EAB information after EABstatus change has been detected through paging messages because the MTCdevices might not actually need the EAB information and also not all MTCdevices would want to access the network.

Therefore, since it appears that both the first and the second proposedmethod are not completely satisfactory, another solution would berequired to alleviate the shortcomings of current proposals, such as asolution to resolve the problems of high paging overhead andnon-necessary impact on the MTC devices when paging messages are used.

SUMMARY OF THE DISCLOSURE

Accordingly, the disclosure provides a method and a user equipment fornotifying parameter changes of an access control mechanism.

In one of the exemplary embodiments, the disclosure directs toconfiguring, in a system information block, a parameter of the accesscontrol mechanism, wherein the access control mechanism bars at leastone access class of the multiple access classes, and the parameter ofthe access control mechanism indicates that a first access class of themultiple access classes has been barred; transmitting a first pagingmessage which comprises an indicator indicating that the parameter of anaccess control mechanism has been modified; not allowing any randomaccess associated with the first access class in response to the firstaccess class being barred; configuring, in the system information block,the parameter of the access control mechanism, wherein the parameter ofthe access control mechanism indicates that the first access class ofthe multiple access classes is no longer barred; transmitting a secondpaging message which comprises the indicator indicating that theparameter of the access control mechanism has been modified; andallowing a random access associated with the first access class inresponse to the first access class no longer being barred.

The disclosure directs to a user equipment which includes not limited toa transceiver; and a processor coupled to the transceiver and configuredto: configure, in a system information block, a parameter of the accesscontrol mechanism, wherein the access control mechanism bars at leastone access class of the multiple access classes, and the parameter ofthe access control mechanism indicates that a first access class of themultiple access classes has been barred; transmit, via the transceiver,a first paging message which comprises an indicator indicating that theparameter of an access control mechanism has been modified; not allowany random access associated with the first access class in response tothe first access class being barred; configure, in the systeminformation block, the parameter of the access control mechanism,wherein the parameter of the access control mechanism indicates that thefirst access class of the multiple access classes is no longer barred;transmit, via the transceiver, a second paging message which comprisesthe indicator indicating that the parameter of the access controlmechanism has been modified; and allow a random access associated withthe first access class in response to the first access class no longerbeing barred.

The accompanying drawings are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of thedisclosure and, together with the description, serve to explain theprinciples of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the communication system in accordance with anexemplary embodiment of the present disclosure.

FIG. 2A illustrates the first variation of the first underlying conceptof this present disclosure.

FIG. 2B illustrates the second variation of the first underlying conceptof this present disclosure.

FIG. 3 illustrates the first exemplary embodiment of the presentdisclosure.

FIG. 4 illustrates the second exemplary embodiment of the presentdisclosure.

FIG. 5 illustrates the EAB procedure from the point of view of an eNB.

FIG. 6 illustrates the EAB procedure from the point of view of a MTCdevice according to the first exemplary embodiment.

FIG. 7 illustrates the EAB procedure from the point of view of a MTCdevice according to the second exemplary embodiment.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

Reference will now be made in detail to the present embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or like parts.

The term “eNodeB” or “eNB” in this disclosure may be, for example, abase station (BS), a Node-B, an advanced base station (ABS), a basetransceiver system (BTS), an access point, a home base station, a relaystation, a scatterer, a repeater, an intermediate node, an intermediary,and/or satellite-based communication base stations, and so like.

The term “user equipment” (UE) in this disclosure may be, for example, amobile station, an advanced mobile station (AMS), a server, a client, adesktop computer, a laptop computer, a network computer, a workstation,a personal digital assistant (PDA), a tablet personal computer (PC), ascanner, a telephone device, a pager, a camera, a television, ahand-held video game device, a musical device, a wireless sensor, and solike. In some applications, a UE may be a fixed computer deviceoperating in a mobile environment, such as a bus, train, an airplane, aboat, a car, and so like.

FIG. 1 illustrates a communication system according to an exemplaryembodiment. The communication system at least includes an eNodeB (101)in communication with at least one UEs (103, 105, . . . 10 x) inaccordance with the LTE communication standard. Each UE contains, forexample, at least a transceiver circuit (111), an analog-to-digital(A/D)/digital-to-analog (D/C) converter (113), and a processing circuit(115). The transceiver circuitry (111) is capable of transmitting uplinksignal and/or receives downlink signal wirelessly. The transceivercircuitry (111) may also perform operations such as low noiseamplifying, impedance matching, frequency mixing, up or down frequencyconversion, filtering, amplifying, and so like. The transceivercircuitry (111) also includes an antenna unit (117). Theanalog-to-digital (A/D)/digital-to-analog (D/C) converter (113) isconfigured to convert from an analog signal format to a digital signalformat during downlink signal processing and digital signal format toanalog signal format during uplink signal processing. The processingcircuit (115) is configured to process digital signal and to performprocedures of the proposed method for data transmission in accordancewith exemplary embodiments of the present disclosure. Also, theprocessing circuit (115) may include a memory circuit (116) to storedata or record configurations assigned by the eNB (101). The eNB (101)contains similar elements including a transceiver unit (121) and aanalog-to-digital (A/D)/digital-to-analog (D/C) converter (119) whichlead to the converted digital signal to be processed by its processingcircuitry (117) as well as using the memory circuit (118) so as toimplement the method for data transmission in accordance with exemplaryembodiments of the present disclosure.

In this disclosure, a method and an apparatus based on FIG. 1 using thesame method which notifies access control information (e.g. EAB) basedon previously said “notification of EAB information update throughpaging” is proposed. However, in this disclosure, the network couldconsume less paging overhead in comparison to the previously said“notification of EAB information update through paging” as only MTCdevices which need EAB information would actually try to acquire theEAB-SIB. Accordingly, the proposed notification scheme would consumeless paging overhead during the process of notifying the latest EABstatus in comparison with conventional method and would more effectivelyalleviate the overloading of PRACH of the LTE communication system.

The first underlying concept of this present disclosure is for the BS tobroadcast through the paging channel (PCH) a paging message whichnotifies whether the access control mechanism is enabled or disabled andto notify the change of states of the access control mechanism includingthe specific changes of the EAB parameters. In other words, the pagingmessage would contain specific information which provides EAB updatestatus. The enabling or disabling of the access control mechanism is fora specific access class (e.g. MTC UE with access class 0-9). The accesscontrol mechanism would affect MTC devices but not H2H devices. Thesecond underlying concept of this present disclosure is for the MTCdevices to decide whether to acquire EAB-SIB not only based on the EABnotification from paging messages but also the current statuses of eachMTC device. The first concept and the second concept are to be presentedwith further detail.

The first variation of the first underlying concepts of this presentdisclosure is to use a binary indicator in the paging channel throughthe paging channel (PCH) to notify whether an access control (e.g. EAB)is enabled or disabled in accordance with a current format of the LTEcommunication systems. For instance, a TRUE or FALSE state (e.g. a firstand a second state) represented by a single bit in a paging messagecould be used to represent whether the EAB has been activated or not. Inother words, a paging message would contain an EAB status bit and bebroadcasted through the paging channel (PCH). The first state of the EABstatus bit could be a one, and the second state of the EAB bit could bea zero and vice versa. When the EAB has been activated, the networkwould notify MTC devices by broadcasting the EAB status bit equals TRUEthrough PCH. When the EAB is disabled, the network would notify MTCdevices by broadcasting the EAB status bit equals FALSE through PCH.

FIG. 2A illustrates the first variation of the first underlying conceptof this present disclosure. In step 201, if a paging message contains aEAB status equals a TRUE state (e.g. EAB status=1), then in step 202,the EAB is set to be activated by the BS. In step 201, if a pagingmessage contains an EAB status equals a FALSE state (e.g. EAB status=0),then in step 203, the EAB is set to be disabled by the BS.

While the EAB is activated, any EAB parameter change would not triggerthe network to send paging messages, which is different from theconventional method. Also, if an other purpose paging (i.e. pagingunrelated to EAB) is needed, the network would send the paging messagingcontaining EAB=TRUE if the EAB is activated. Otherwise, if an otherpurpose paging is needed while the EAB is disabled, the network wouldsend the paging message containing EAB=FALSE if the EAB is disabled. Inthis way, the presence of the EAB status bit could provide moreinformation about the EAB status than the conventional method frompaging message. Also since any EAB parameter change will not trigger thenetwork to send paging messages, paging overhead can be minimized duringthe duration of EAB enable or disable.

The second variation of the first underlying concept is to notify notonly whether the EAB has been activated or disabled but also to notifywhether the EAB parameters have been changed. In order for this conceptto be implemented, the network would use multiple EAB indicator bits torepresent both the EAB status and subsequent changes to the EAB status.

For instance, if two indicating bits are used, then there could be fourpossible states. The first state could be 00, and the second, third, andfourth state could be respectively 01 or 10 or 11. If the first statecould indicate EAB disabled, then the second, third, and fourth statecould indicate that the EAB has been activated. The cyclical changesfrom the second state, to the third state, to the fourth state, to thesecond state, and etc could indicate the change of EAB parameters.

For instance, if EAB is disabled, the paging message through the PCHwould contain bits 00 which indicates that the EAB status is disabled.If the EAB is activated, the network would notify MTC devices by sendingpaging messages with the EAB status bits 01 which indicates that the EABstatus has been activated. During the duration of the activation of theEAB, if the EAB parameters were to change, the EAB indicating bits couldchange from 01 to 11 or 10. Therefore, when the EAB information changesafter EAB has been activated, the network would send paging message withthe EAB indicator=11. The MTC devices would know that the EABinformation has bee updated since the EAB indicator has changed from 01to 11. In this way, the MTC devices could prevent wasting resources toobtain the same EAB information which has not been updated from theduplicate paging messages. The duplicate paging message is forincreasing the reliability that the MTC devices would receive the pagingmessage. If the paging message is caused by other purpose paging whilethe EAB is still activated, the EAB status indicator would remainunchanged. When the EAB is disabled, the network would send the pagingmessage containing the EAB status indicator=00.

FIG. 2B illustrates the second variation of the first underlyingconcept. In 251, a paging message has been broadcasted by a BS or eNB.The paging message contains information as for whether the EAB has beendisabled or activated. If the EAB has been disabled, then the EAB statusindicator in the paging message would have been set to be 00. If EAB hasbeen activated, then in 252, the EAB status indicator could be set toany of the 01, 10, or 11 indicating bits. Each time when the EABinformation is updated, the indicating bits would cycle among 01, 10,and 11.

For the second underlying concept, MTC devices would decide whether toacquire the EAB-SIB not only based on the EAB notification from pagingmessages but also decides based on the current status of the MTC devicesthemselves. In other words, if an MTC device is unbarred, it does notacquire EAB-SIB right away according to the conventional method, burrather the MTC device would postpone acquiring of the EAB-SIB until itdecides to perform random access after receiving the EAB notificationfrom a paging message. If a MTC device finds itself barred by the EAB,the barred MTC device would later acquire the EAB-SIB according to anevent trigger, such as the timer trigger or receiving an EAB updatenotification from another paging message. Based on the first and thesecond underlying concepts of this present disclosure, two specificembodiments have been proposed.

The first exemplary embodiment is to combined the first variation of thefirst underlying concept with the second underlying concept, that is forusing a binary indicator to notify the whether the EAB has been enabledor disabled through PCH and for a MTC device to decide whether toacquire the EAB-SIB based on its current status.

FIG. 3 illustrates the first exemplary embodiment of the presentdisclosure. Referring to FIG. 3, in 351 when EAB has been enabled oractivated, the network would in send a paging message with an EABstatus=TRUE indication. As a MTC device detects the EAB=TRUE indication,the MTC would in 301 knows that the EAB has been enabled. For the firstembodiment, the MTC stays true to the second underlying concept and doesnot try to acquire the EAB-SIB right away after receiving the pagingmessage with the EAB status=TRUE indication because it has not yet triedto access the network. Also, when the EAB parameter change in 352, thechange of the EAB parameter will not trigger the network to send apaging message to notify the MTC devices and therefore saves pagingoverhead. However, when the network needs to send an other purposepaging in 353 (i.e. normal paging not related to EAB), the network wouldstill include the EAB status=TRUE indication as long as the EAB is stillactivated. In that case, the paged MTC devices would still know in 302know that the EAB is enabled and respond to paging as they normallywould according to conventional procedures.

When the EAB is disabled as in 354, the network would send a pagingmessage with EAB status=FALSE to the MTC devices. The MTC devices wouldin 303 know that the EAB has been disabled and would perform access tothe network normally. Also, as long as the EAB remain disabled, an otherpurpose paging in 355 would contain in the paging message the EABstatus=FALSE indication. The MTC devices would in 304 respond to thepage normally according to conventional procedures and at the same timeknow that the EAB is still disabled.

According to another example of the first embodiment, the change of theEAB status could signal a change in the EAB status. A UE may know thatthe EAB parameter has changed whenever the indicator changes from theEAB status=TRUE to the EAB status to the FALSE state or vice versa. Inanother word, the UE could know that the EAB status has changed when theEAB indicator bit changes from 0 to 1 or 1 to 0. Also for this example,if the indicator does not appear in the paging message, then itsignifies that the EAB has been disabled. Otherwise, the appearance ofthe indicator per se in the paging message signifies that the EAB hasbeen activated. The key concept behind this particular example is to usethe change of EAB indicator bit in the paging message to signal a changein the EAB parameter. As the EAB parameter has been altered by the basestation, the MTC UEs served by the base station would need to fetch andupdate the EAB parameter contained in the system information.

The second exemplary embodiment is to combined the second variation ofthe first underlying concept with the second underlying concept, that isfor using a multi-bits EAB status indicator to notify the whether theEAB has been enabled or disabled and EAB parameters change through PCHand for a MTC device to decide whether to acquire the EAB-SIB based onits current status. FIG. 4 illustrates the second exemplary embodimentof the present disclosure.

Referring to FIG. 4, when EAB is enabled or activated in 451, thenetwork would notify the MTC devices through PCH containing a two bitindicator, EAB status=01 indication. Please note the embodiment is notlimited to the exact binary value nor is it limited to only two bits.When the MTC devices receive the EAB status=01 indication from thepaging message through PCH, they would know that the EAB has beenenabled.

In this exemplary embodiment, a MTC device in general does not yet tryto acquire the EAB-SIB after receiving the paging message with the EABindicator=01 (01 implies EAB=activated) since it has not yet tries toaccess the network. In 452, when the EAB parameter is altered by theeNB, the eNB would transmit a paging message with the EAB status=10indication. As a MTC device compares the newly received EAB statusindicator with the previous EAB status indicator and realizes thedifferences between the two, the MTC device in 402 would know that theEAB parameter has bee changed. During the next time when the EABparameter is altered again, the network would send yet another pagingmessage with the EAB status=11 indication. The paged MTC devices in 403would know that the EAB parameter has been changed again.

In 454 when EAB has been disabled by the eNB, the eNB would send apaging message with the same indicator containing EAB status=00indication. MTC devices in 404 would know that the EAB has beendisabled.

Once a MTC device tries to access the network after detecting that theEAB status indicating bits inform a status of “enabled” or TRUE, itwould first acquire the EAB-SIB before it actually performs a randomaccess procedure. After acquiring the EAB-SIB, if a MTC device findsitself barred by the EAB, the device will wait for a predeterminedperiod and re-acquire the EAB-SIB to check whether itself is stillbarred by the EAB from the EAB parameters. Note that the predeterminedperiod can be determined by the eNB or the MTC device itself. If thebarred device acquires the EAB-SIB and passes the bar by the EAB orfinds that the EAB has been disabled entirely, it would wait for anotherpredetermined period and access the network.

FIG. 5 illustrates the flowchart of notifying the EAB from the point ofview of an eNB. Referring to FIG. 5, in 501, the eNB activates the EABfor a specific access class (e.g. for MTC devices). In 502, the eNBconfigures the EAB parameter in the EAB-SIB as well as configuring theEAB status indicator in the paging message. In 503, the eNB transmits apaging message to inform MTC devices that the EAB has been active. In504, the eNB also broadcast the EAB-SIB contained in the SI which isbroadcasted periodically to MTC devices in range. In 505, the eNBdetermines whether the EAB information containing EAB parameter orstatus needs to be changed. If yes, the eNB re-configures the EABinformation in 502. Otherwise, the eNB would eventually disable the EABwhen it is no longer necessary.

FIG. 6 illustrates the flowchart of handling a paging message containingEAB status indication from the point of view of a MTC device for thefirst exemplary embodiment. First in 601, a MTC device receives a pagingmessage. Next, in 602, the paged MTC would determine whether the EAB hasbeen activated. If no, then the paged MTC device in 608 would performthe conventional access procedure according the LTE specification. Ifthe page MTC learns that EAB has been activated in 602, but the MTC doesnot try to access the network, then the MTC still follows theconventional access procedure in 608 but postpones the acquisition ofthe EAB-SIB until it tries to access the network. However, if the MTCdevice tries to access the network in 603 (i.e. perform a random accessprocedure), it would first need to acquire the EAB-SIB in 604. Afteracquiring the EAB-SIB in 604, the MTC device in 605 would detect whetherit is actually barred by the EAB or unaffected. If the MTC device isunder the bar, the in 606 it would wait for a predetermined periodbefore re-acquire the EAB-SIB in 606. After the predetermined period haselapsed, the MTC device in 607 would check if it has received anotherpaging message during the predetermined period. If the MTC device hasnot received another paging message in 607, the MTC device would acquirethe EAB-SIB in 604.

If the MTC device has received another paging message during thepredetermined period in 607, then in 609 the MTC device would check ifthe EAB has been deactivated. If the EAB has been deactivated in 609(e.g. EAB status bit=FALSE or 0), then in 610, the MTC device wouldaccess the network (i.e. perform a random access procedure) as the MTCdevice normally would. At this point, the EAB process has ended.However, the EAB is still active (e.g. EAB status bit=TRUE or 1), thenthe MTC device would acquire the EAB-SIB in 604. In this way, the MTCdevice does not acquire the EAB-SIB right away after receiving a pagingmessage but postpones acquiring the EAB-SIB until it needs to access thenetwork.

FIG. 7 illustrates the flowchart of handling a paging message containingEAB status indication from the point of view of a MTC device for thesecond exemplary embodiment. First in 701, a MTC device receives apaging message. Next, in 702, the paged MTC would determine whether theEAB has been activated. If no, then the paged MTC device in 709 wouldperform the conventional access procedure according the LTEspecification. If the page MTC learns that EAB has been activated in702, but the MTC does not try to access the network, then the MTC stillfollows the conventional access procedure in 709 but postpones theacquisition of the EAB-SIB until it tries to access the network.However, if the MTC device tries to access the network in 703 (i.e.perform a random access procedure), it would first need to acquire theEAB-SIB in 704. After acquiring the EAB-SIB in 704, the MTC device in705 would detect whether it is actually barred by the EAB or unaffected.If the MTC device is under the bar in 705, then in 706 it would wait foranother paging message to arrive.

In 707, if the paging message has not arrived, the procedure would loopback to 706. If another paging message has arrived in 707, then in 708,the MTC device checks if the EAB parameter has changed from the pagingmessage (i.e. by following the bit pattern as in FIG. 2B). If the EABparameter has changed in 708, then it would check in 710 if the EAB hasbeen deactivated. If the EAB has been deactivated in 710 (e.g. EABstatus bit=00 as in FIG. 2B), then in 711, the MTC device would accessthe network (i.e. perform a random access procedure) as the MTC devicenormally would. At this point, the EAB process has ended. However, theEAB is still active (e.g. EAB status bit=01, 10, or 11), then the MTCdevice would acquire the EAB-SIB in 704. In this way, the MTC devicedoes not acquire the EAB-SIB right away after receiving a paging messagebut postpones acquiring the EAB-SIB until it needs to access thenetwork.

In Summary, a method and an apparatus for notifying activations ofextended access barring (EAB) and updates of EAB information in thefield of Long Term Evolution (LTE) wireless communication systems havebeen proposed. In view of the aforementioned descriptions, the eNBnotifies MTC devices of EAB changes through the paging message. Thenetwork could use either a single bit EAB status indicator to notifywhether the EAB has been enabled or disabled or use multiple bits EABindicator to represent different EAB parameter changes. Based on thepresent disclosure, the network could reduce the paging overhead byrequire the MTC device to acquire the EAB-SIB only when it needs the EABinformation.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of thedisclosed embodiments without departing from the scope or spirit of thedisclosure. In view of the foregoing, it is intended that the disclosurecover modifications and variations of this disclosure provided they fallwithin the scope of the following claims and their equivalents.

What is claimed is:
 1. A method used by a base station for notifying aspecific access class of multiple access classes of parameter changes ofan access control mechanism, the method comprising: configuring, in asystem information block, a parameter of the access control mechanism,wherein the access control mechanism bars at least one access class ofthe multiple access classes, and the parameter of the access controlmechanism indicates that a first access class of the multiple accessclasses has been barred; transmitting a first paging message whichcomprises an indicator indicating that the parameter of an accesscontrol mechanism has been modified; not allowing any random accessassociated with the first access class in response to the first accessclass being barred; configuring, in the system information block, theparameter of the access control mechanism, wherein the parameter of theaccess control mechanism indicates that the first access class of themultiple access classes is no longer barred; transmitting a secondpaging message which comprises the indicator indicating that theparameter of the access control mechanism has been modified; andallowing a random access associated with the first access class inresponse to the first access class no longer being barred.
 2. The methodof claim 1, wherein the parameter of the access control mechanismindicates that a second access class of the multiple access classes hasbeen barred, and claim 1 further comprising: not allowing any randomaccess associated with the second access class in response to the secondaccess class being barred
 3. The method of claim 1, wherein theindicator indicates multiple states represented by different binaryvalues, the multiple states comprise a first state and a second state,and changing from the first state to the second state indicates that theparameter of the access control mechanism has been modified.
 4. Themethod of claim 3, wherein the indicator indicates at least four statesby at least two binary bits, wherein the multiple states furthercomprise a third state and a fourth state.
 5. The method of claim 4,wherein each of the first state, the second state, and the third stateindicates an activation of the access control mechanism, and the fourthstate indicates a disablement of the access control mechanism.
 6. Themethod of claim 5, wherein any change of the indicator among the firststate, the second state, and the third state indicates that theparameter of the access control mechanism has been modified.
 7. Themethod of claim 5 further comprising: activating the access controlmechanism; and configuring the indicator as the first state, the secondstate, or the third state.
 8. The method of claim 7 further comprising:disabling the access control mechanism; and configuring the indicator asthe fourth state.
 9. The method of claim 1, wherein the access controlmechanism is extended access barred (EAB) mechanism.
 10. The method ofclaim 1, wherein the system information block is broadcastedperiodically.
 11. A base station comprising: a transceiver; and aprocessor coupled to the transceiver and configured to: configure, in asystem information block, a parameter of the access control mechanism,wherein the access control mechanism bars at least one access class ofthe multiple access classes, and the parameter of the access controlmechanism indicates that a first access class of the multiple accessclasses has been barred; transmit, via the transceiver, a first pagingmessage which comprises an indicator indicating that the parameter of anaccess control mechanism has been modified; not allow any random accessassociated with the first access class in response to the first accessclass being barred; configure, in the system information block, theparameter of the access control mechanism, wherein the parameter of theaccess control mechanism indicates that the first access class of themultiple access classes is no longer barred; transmit, via thetransceiver, a second paging message which comprises the indicatorindicating that the parameter of the access control mechanism has beenmodified; and allow a random access associated with the first accessclass in response to the first access class no longer being barred. 12.The A base station of claim 11, wherein the parameter of the accesscontrol mechanism indicates that a second access class of the multipleaccess classes has been barred, and claim 11 further comprising: notallowing any random access associated with the second access class inresponse to the second access class being barred.
 13. The A base stationof claim 11, wherein the indicator indicates multiple states representedby different binary values, the multiple states comprise a first stateand a second state, and changing from the first state to the secondstate indicates that the parameter of the access control mechanism hasbeen modified.
 14. The A base station of claim 13, wherein the indicatorindicates at least four states by at least two binary bits, wherein themultiple states further comprise a third state and a fourth state. 15.The A base station of claim 14, wherein each of the first state, thesecond state, and the third state indicates an activation of the accesscontrol mechanism, and the fourth state indicates a disablement of theaccess control mechanism.
 16. The A base station of claim 15, whereinany change of the indicator among the first state, the second state, andthe third state indicates that the parameter of the access controlmechanism has been modified.
 17. The A base station of claim 15, whereinthe processor is further configured to: activate the access controlmechanism; and configure the indicator as the first state, the secondstate, or the third state.
 18. The A base station of claim 7, whereinthe processor further configured to: disable the access controlmechanism; and configure the indicator as the fourth state.
 19. The Abase station of claim 1, wherein the access control mechanism isextended access barred (EAB) mechanism.
 20. The A base station of claim1, wherein the system information block is broadcasted periodically viathe transceiver.